Map: Dysart High School

YOUNGTOWN, Ariz. -- Maricopa County sheriff's deputies arrested a 16-year-old boy who allegedly brought a loaded gun to school and threatened to shoot another student.

Authorities at Dysart High School in El Mirage requested a welfare check on a 14-year-old boy who was absent from school Tuesday and may have been suicidal, according to sheriff's office spokesman Sgt. Brandon Jones.

Deputies went to the boy's home in Youngtown and his mother told them that her son was threatened at the school bus stop that morning. The 16-year-old suspect reportedly showed the victim a gun and said he was going to kill him.

Deputies waited for the suspect to exit the school bus Tuesday afternoon and questioned him. When they searched his belongings, they found a loaded .25-caliber handgun in his possession.

Jones said the teen admitted to taking the gun onto the bus and to school. He was arrested and faces felony charges of aggravated assault, possession of firearm by prohibited persons, misconduct involving weapons and theft.

The suspect's name has not been released.

"This is the third recent incident where my deputies have investigated school violence," Sheriff Joe Arpaio said in a news release. "It is exactly why I am providing active shooter training for members of my school posse patrol program this weekend, and why I sent out the armed posse in the first place. We will continue to be vigilant in order to protect the schools."